Universal sled for adaptation of existing sheet stack processing machine for use with sheet handling system

ABSTRACT

A universal sled for adapting an existing sheet processing station for use with a sheet handling system, a sheet handling system including an existing sheet processing station, and a method of performing the same. The sled is supported on and moveable relative to a platform of the existing sheet processing station. The sled includes a plurality of parallel support surfaces that collectively form a sheet support surface that may be intermeshed with a plurality of parallel support surfaces that form a sheet support surface of a cart, the sheet support surfaces of the cart being intermeshable with the support surfaces of other modules of the system.

FIELD OF THE INVENTION

The invention relates to a document processing system utilizing a transport system for passing sheet stacks between processing modules to provide optionally modular post-printer document processing. More particularly, the invention relates to a method and a sled arrangement for adapting existing sheet processing machine to be utilized with a sheet stack handling system.

BACKGROUND OF THE INVENTION

In the sheet finishing industry, sheet stacks are transferred between processing equipment as various steps are performed on the stacks of sheets. This transfer is typically classified as “in-line” or “off-line,” and sometimes “near-line.”

“In-line” refers to two pieces of processing equipment having their sheet paths joined together such that individual sheets are passed from one system to the other sequentially and processed as such. While there are many examples of such “in-line” processing, one such prominent example is designed following the Xerox DFA (Digital Finishing Architecture) Standard. The DFA protocol spells out mechanical and software specifications for attaching finishing machinery to DFA compatible Xerox sheet printers. Many vendors make secondary equipment to create systems using this standard, including Standard Finishing, C. P. Bourg, Duplo, and others.

“In-line” systems are advantageous in that they require minimal operator interaction, and therefore, have lower overhead and least opportunity for operator error. The entire system is locked in a one-to-one speed relationship, however, limiting the performance of the entire system to that of the slowest component. Accordingly, a major disadvantage of the “in-line” system is the lack of a buffer to allow for continued processing by some portions of the system if other portions of the system temporarily cease operations. Another disadvantage is reduced versatility from two types of processing modules that are complexly coupled, inhibiting their separate use for other functions.

“Off-line” refers to sheets being transferred in some non-automatic fashion, usually in stacks of sheets. Examples include simple carts to and from which sheet stacks are manually transferred by an operator. “Off-line” systems have the advantage of being able to match a slower module to a faster device, optimizing overall performance. It is commonly accepted that a ratio of 2:1 or greater may be matched with such in-line processing. Additionally, the components of such “off-line” processing are not tightly coupled, allowing for more versatile use of each module. “Off-line” processing, however, necessarily requires greater operator interaction than “in-line” processing, increasing labor costs as well as the opportunity for operator error in the form of both mechanical damaged sheet stacks or movement of the stacks out of sequence, when sequence is important.

“Near-line” refers to a special case of “off-line” processing where the carts are more elaborate and custom-mated to automatically receive and discharge sheet stacks. The stacks may be electronically tracked to ensure sequence of processing, as disclosed in U.S. Pat. No. 6,192,295 B1 to Gunther. One example of this type of “near-line” processing is marketed by GTI. In the GTI cart system, stacks are laid on a cart and the cart is manually rolled to a feeder. The GTI cart is designed to custom mate to the GTI stacker and GTI feeder. Although operator error is less than the opportunity with true “off-line” the chance is not eliminated. The GTI cart has a clamping system that secures the stacks from movement, however, the system requires considerable operator effort to operate.

PCT Application PCT/US0239834 filed Dec. 13, 2002 by the assignee of the present application proposed a document handling system which utilized one or more of an elevator transfer station, modular transfer station, transportation cart, storage station, and/or modular processing station to provide in-line document processing in a modular environment while allowing the use of one or more modular processing stations in an off-line manner without disconnection of the module from other modules that form part of the sheet handling system. Each of the transfer station, cart, and storage station included a plurality of elongated support surfaces or fingers to create a sheet support surface, slotted platform or deck such that the alternating fingers and slots of the transfer station or cart storage station receive the alternating slots and fingers of the cart to transfer stacks of sheets supported on the upper surface to and from the cart and transfer station or storage station. Stacks of sheets were transportable between adjacent processing modules by similarly intermeshed transfer stations or intermediate belts, rollers, or the like. The entirety of PCT Application PCT/US0239834 is included herein by reference for everything that it discloses.

Unfortunately, however, a user may own equipment that is unable to interact with the equipment of the proposed document handling system. As a result, additional user intervention is required that would introduce the opportunity for operator handling and processing errors and mishaps, not to mention the increased labor costs involved. Replacement of all equipment with such system compatible equipment is potentially an expensive endeavor that a user may wish to delay, prolong, or avoid altogether.

OBJECTS AND BRIEF SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a sled for use in adapting a sheet processing machine for use with a sheet handling system. The sled is movably supported on a platform of the existing machine such that a stack of sheets supported on the upper surface of the sled may be move into or out of a feed or output position relative to the machine. The sled comprises a base from which a plurality of elongated support surfaces for supporting the stack of sheets. The sled elongated support surfaces are spaced to permit the location of the plurality of parallel surfaces of a movable cart such that a stack of sheet supported one may be transferred to the other. The sled further includes a plurality of rotatable supports that support the sled on the platform and facilitating relative movement between the plurality of sled elongated support surfaces and the platform.

The sled preferably includes a locking arrangement that selectively secured the sled to the platform. The locking arrangement preferably comprises at least one bracket secured to the platform and the sled comprises at least one slot, the slot being disposed and sized to slide along the bracket. The sled may alternately or additionally comprises a hook disposed and sized to selectively engage the edge of the platform.

A method according to the invention comprises providing an existing machine with such a sled. A sheet handling system according to the invention comprises such a transportation cart, at least one existing processing station for performing an operation on said successive sheets or stacks of sheets, the processing station comprising a platform having an upper surface, such a sled, and at least one module selected from the group consisting of an elevator transfer station, a modular transfer station, a storage station, and a second modular processing station for performing an operation on said successive sheets or stacks of sheets. The at least one module and the sled comprise a plurality of elongated support surfaces disposed to collectively present sheet support surfaces that are intermeshable with such elongated support surfaces of the cart.

These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cart arrangement for use in a document handling system.

FIG. 2 is a perspective view of a sled constructed in accordance with teachings of the invention and or use in adapting equipment to be utilized with a document handling system.

FIG. 3 is a bottom view of the sled of FIG. 2.

FIG. 4 is a side view of the sled of FIG. 2.

FIG. 5 is an end view of the sled of FIG. 2.

FIG. 6 is a plan view of the sled of FIG. 2 supported and locked in position at the edge of a platform.

FIG. 7 is a side cross-sectional view of the center finger of the sled of FIG. 2.

FIG. 8 is a plan view of the sled of FIG. 2 supported in position at the edge of a platform and supporting a stack of sheets.

FIG. 9 is an end view of the sled of FIG. 8.

FIG. 10 is a perspective view of the sled supporting a stack of sheets, as in FIGS. 8 and 9.

FIG. 11 is a side cross-sectional view of the center finger of the sled supporting a stack of sheets as in FIGS. 8-10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, there are shown in FIG. 1 an exemplary moveable transportation cart 20 for use in a sheet stack handling system such as is disclosed in detail in PCT Application PCT/US0239834. The entirety of PCT Application PCT/US0239834 is included herein by reference for everything that it discloses. The cart 20 may operate electrically, hydraulically, manually, or by any other appropriate method. The cart 20 includes a slotted deck 22 having spaced deck fingers 24 having open deck slots 26 disposed therebetween. The cart 20 includes a plurality of casters 28, rollers, or another mechanism for moving the cart 20. As explained in greater detail in the PCT application, the transportation cart 20 is utilized to transport stacks of sheets between various sheet stack processing modules (not shown) equipped with similarly spaced slotted platforms. Existing sheet or sheet stack processing modules that are not constructed in accordance with the invention set forth in the PCT application, however, do not typically have such slotted platforms for utilization with the inventive handling system. Such existing sheet or sheet stack processing module may be, for example, any of the various types of modules, including finishing machines such as binders, inserters, envelope stuffers, sealers, punches, laminator, stackers, or any number of types of processing devices.

In accordance with the invention, there is provided a universal sled 30 that may be utilized to adapt sheet stack processing equipment to interact with the handling system of the PCT application. The sled 30 is preferably placed on an input or output platform 40 of sheet stack processing equipment such that a stack of sheets supported on the sled 30 may be moved along the platform 40 to position that sled 30 at an input or output of such equipment. An exemplary such sled 30, constructed in accordance with teachings of the invention, is shown in FIG. 2. The sled 30 includes a base portion 32 from which a plurality of substantially parallel support surfaces or fingers 34 extend separated by a plurality of spaces 36, here, elongated support surfaces. According to an important feature of the invention, the sled fingers 34 are sized and disposed such that they may intermesh with the fingers 24 of a transportation cart 20 for use in a sheet stack handling system such as is disclosed in detail in PCT Application PCT/US0239834. As a result, the sled 30 may be placed on an input or output platform 40 of sheet processing equipment such that the fingers 24, 34 of the cart 20 and sled 30 may be intermeshed to transfer a stack of sheets from one to the other. While the sled 30 is described herein as including a plurality of parallel fingers 34, it will be appreciated by those of skill in the art that the sled could have an alternate design, including the provision of a substantially continuous upper surface.

While the size and spacing of the fingers 34 may be of any appropriate dimensions, typically, 3-7 fingers 34 will be provided, and the spacing between the fingers 34 will be on the order of no more than a couple of inches in order to provide adequate support to the stack of sheets. Preferably, the fingers 34 are on the order of 1-2 inches wide, with spacing between the fingers 34 similarly running on the order of 1-2 inches, most preferably 1-1¼ wide fingers spaced 1¼ inches apart. Alternately stated, measuring the finger spacing from centerline of the finger to centerline of the finger, the centerlines are preferably spaced on the order of 2 to 4½ inches apart, most preferably 2-2½ inches apart. It will be appreciated by those of skill in the art that the fingers 34 may have a uniform width, or they may have a varied cross-section. The fingers 34 may be of any appropriate design. For example, they may be rounded or tapered at the ends 35 in order to facilitate the intermeshing with the fingers of the cart or other device.

The platform 40 itself may be provided as a standard part of the processing equipment, or it may be retrofit to equipment that includes an alternate input/output. As will be appreciated by those of skill in the art, the platform 40 preferably includes an elevator mechanism whereby the platform 40 may be moved upwards or downwards to properly position the sled 30 to a feeding or output mechanism.

In order to provide a degree of movement of the sled 30 on the platform 40, one or both of the platform 40 and/or the sled 30 preferably includes one or more reduced friction surfaces 38 that allow the sled 30 be easily moved along the platform 40 to properly position the sled 30 at the feed or output of the equipment. In the currently preferred embodiment, the low friction surfaces are so-called furniture glides. It has been determined that such furniture glides provide an adequately low friction interface between the sled 30 and the platform 40 to allow the operator to readily move the sled 30 into a desired position, even when supporting a stack of sheets. The glides 38, however, do not allow the sled 30 to freely move as a result of miscellaneous force inputs such as vibrations as an elevator lifts the platform into a desired position. It will be appreciated, however, that an alternate arrangement may be provided, such as ball bearings, casters, rollers, or a combination of such transport devices. Further, the low friction support surface may be continual along the bottom surface of the sled 30 or the platform 40, rather than at a plurality of individual support points. Alternately, the platform 40 may include a plurality of air jets to provide an air glide surface for the sled 30.

According to another feature of the invention, the sled 30 may preferably be positioned relative to the feed mechanism of the equipment to feed from any desired lead edge. As a result, the footprint or overall plan dimensions of the sled 30 are preferably such that it is slightly smaller than the dimensions of the sheets to be transferred. For example, if 19.20 by 12.6 inch paper is to be utilized, the sled is preferably sized to have outside plan dimensions of 18.25 by 10.25 inches of the sled. In this way, the any of the corners and/or sides of the supported stack of sheets may be located as the locating corner or lead edge, respectively. The sled 30 would typically have a footprint no larger than 15 by 20 inches.

The sled 30 may additionally or alternately include one or more recesses or protrusions that facilitate interaction with structure of the platform or machine. For example, the embodiment of the sled 30 shown in the figures includes a number of recesses 39 that may receive aligning guides from the platform or machine. Alternate aligning recesses, for example, may be provided in the bottom or top surfaces of the sled 30.

Additionally, in order to facilitate the transfer of a stack of sheets from the cart 20 to the sled 30, the sled 30 and/or the platform 40 are preferably provided with an automatic locking mechanism for securing the sled 30 in position at the edge 48 of the platform 40 during the transfer and prevent the sled 30 from tipping under the weight of a stack of sheets. In the illustrated embodiment (see FIG. 6), the platform 40 is provided with a pair of Z-brackets 42, and the sled 30 is provided with elongated slots 50 along two of the fingers 34, here, the outermost side surface of the outermost fingers 34. The brackets 42 are secured to the platform 40 at their base 44 by any appropriate method. The brackets 42 are disposed and spaced such that the free ends 46 of the brackets 42 engage the slots 50 of the sled 30 as the sled is moved toward the edge 48 of the platform 40. The sled 30 is free to slide forward to the edge 48 of the platform 40 until such time as the free ends 46 of the brackets 42 reach the innermost end of the slots 50. In this way, the engagement of the brackets 42 with the slots 50 will prevent the sled 30 from sliding off of or tipping over the edge of the platform 40. It will be appreciated that the combination of the brackets 42 and the slots 50 may be alternately designed and arranged and still limit relative movement between the sled 30 and the platform 40.

In order to maintain the sled 30 at the edge 48 of the platform 40 as the slotted deck 22 of cart 20 engages the fingers 34 of the sled 30 for transfer of the stack of sheets, the automatic locking arrangement further comprises a lock that engages the edge 48 of the platform 40 once the sled 30 is slid into position at the edge 48. As may best be seen in FIG. 7, the lock comprises a pawl 54 pivotably disposed on a shaft 58 in an opening 51 in one of the fingers 34. The pawl 54 is more heavily weighted along one side of the shaft 58 such that it is biased with the hook 56 at the end of the pawl 54 in the downward position. As a result, as the sled 30 is advanced to the edge 48 of the platform 40, the hook 56 at the end of the pawl 54 drops downward to engage the edge 48 of the platform 40 as it passes the edge 48 (see also FIG. 2). In this way, the hook 56 in engagement with the edge 48 of the platform 40 prevents the sled 30 from being moved backward, away from the edge 48.

As shown in FIGS. 2 and 7, when the hook 56 is in engagement with the edge 48 of the platform 40, the end of the pawl 54 opposite the hook 56, i.e., the end 52 is in an upward position wherein it breaks the top plane of the sled 30. As a result, as a stack of sheets is placed on the sled 30, the weight of the stack causes the pawl 54 to pivot to a generally horizontal position, as shown in FIGS. 10 and 11, causing the hook 56 to disengage the edge of the platform 48. The sled 30 may then be pushed rearward, sliding the slots 50 along the brackets 42 until they disengage, allowing the sled 30 to be positioned as desired on the platform for further action on the same. Additionally, the sled 30 and/or the platform 40 may include an arrangement for preventing relative movement between the sled and the platform in place at the input or output of the machine. By way of example only, such a locking arrangement may include structure such as a clamp or hook that engages the sled or the platform, motion arresters for rollers or the like supporting the sled, or a magnetic arrangement.

It will be appreciated by those of skill in the art that the locking mechanism may be other than as described herein. The overall locking arrangement for securing the sled 30 to the edge 48 of the platform 40 is preferably as automatic as possible in order to minimize intervention by the user.

In summary, the universal sled 30 arrangement provides a means of adapting an existing piece of sheet processing equipment to interact with an overall sheet transportation system. In use, a stack of sheets is supported on the slotted deck 22 of the sled 20. The sled 30 is moved into position at the edge 48 of the platform 40. In the embodiment illustrated, the sled 30 is moved to advance the slots 50 along the brackets 42 until the pawl 54 drops into position with the hook 56 extending over the edge 48 of the platform 40. The slotted deck 22 of the cart 20 is moved into position with the deck finger 24 alternating with the fingers 34 of the sled 30. The slotted deck 22 of the cart 20 is then lowered until the supported stack of sheets transfers from the slotted deck 22 to the sled 30. It will be appreciated, however, that the sled could include an elevator-type of arrangement wherein the upper surface of the sled may be moved to facilitate the transfer of the stack. In the current embodiment, however, as the stack is lowered onto the sled 30, the weight of the stack pivots the pawl 54, causing the hook 56 to release the edge 48 of the platform 40. The slotted deck 22 of the cart is then withdrawn, and the sled 30 is slid backwards, the slots 50 sliding along the brackets 42 until the sled 30 is disengaged from the platform 40.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

It will be appreciated that a novel and useful universal sled and platform arrangement has been disclosed herein by way of examples, and that it is the claims, rather than these examples that define the scope of the invention. In particular, preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 

1. A sled for use in adapting a sheet processing machine for use with a sheet handling system, the machine comprising a platform, the sheet handling system comprising a cart having a plurality of parallel cart surfaces forming a sheet support surface for supporting a stack of sheets, the sled comprising a plurality of elongated support surfaces for supporting the stack of sheets, said sled elongated support surfaces being secured together in their relative positions, the plurality of sled elongated support surfaces being spaced to permit the location of the plurality of parallel cart surfaces, and a lower surface adapted to be disposed toward the platform, the sled being selectively movable relative to the platform.
 2. The sled of claim 1 further comprising at least one low friction support disposed subjacent at least a portion of the lower surface of the sled, the low friction support supporting the sled on the platform and facilitating relative movement between the sled lower surface and the platform.
 3. The sled of claim 2 wherein the low friction support comprises at least one of a polytetrafluoroethylene surface, furniture glide, caster, roller, or ball bearing.
 4. The sled of claim 1 further comprising a base, said plurality of sled elongated support surfaces extending from the base, said base securing the sled elongated support surfaces in their relative positions.
 5. The sled of claim 1 further comprising a locking arrangement, the locking arrangement selectively securing the sled to the platform.
 6. The sled of claim 2 wherein the locking arrangement limits relative movement between the sled and the platform.
 7. The sled of claim 5 wherein the locking arrangement comprises at least one bracket secured to the platform and the sled comprises at least one slot, the slot being disposed and sized to slide along the bracket.
 8. The sled of claim 5 wherein the platform comprises an edge, and the locking arrangement secures the sled to the edge of the platform.
 9. The sled of claim 8 wherein the locking arrangement comprises at least a hook, the hook being coupled to the sled and disposed and sized to selectively engage the edge of the platform.
 10. The sled of claim 9 wherein the locking arrangement comprises a pivotably mounted pawl, the pawl including the hook.
 11. The sled of claim 1 wherein the sled has an overall footprint, said foot print being no greater than 15 by 20 inches.
 12. The sled of claim 1 wherein the elongated support surfaces comprise 3-7 fingers.
 13. The sled of claim 1 wherein the elongated support surfaces have an upper surface width, the upper surface width of at least a portion of the elongated support surfaces being 1-2 inches wide.
 14. The sled of claim 1 wherein at least one of the elongated support surfaces has a tapered leading edge.
 15. The sled of claim 1 wherein the elongated support surfaces are spaced 1-2 inches apart.
 16. The sled of claim 1 wherein the elongated support surfaces each have a centerline, and the distance between the centerlines of at least two adjacently disposed elongated support surfaces is 2-4 1/2 inches.
 17. A sheet handling system for performing at least one operation on successive sheets or stacks of sheets, the document handling system comprising: a transportation cart, the transportation cart comprising a plurality of elongated support surfaces disposed to collectively present a cart sheet support surface, at least one processing station for performing an operation on said successive sheets or stacks of sheets, the processing station comprising a platform having an upper surface, a sled comprising a plurality of elongated support surfaces collectively presenting a sled sheet support surface, said sled being supported on the upper surface and being movable in at least one direction in a plane parallel to the upper surface, and at least one module selected from the group consisting of an elevator transfer station, a modular transfer station, a storage station, and a second modular processing station for performing an operation on said successive sheets or stacks of sheets, said at least one module comprising a plurality of elongated support surfaces disposed to collectively present a sheet support surface, at least a portion of said plurality of elongated support surfaces of the transportation cart and the sled being sized and disposable to intermesh to create a joint sheet support surface such that sheets or stacks of sheets disposed on the plurality of elongated support surfaces of one of the transportation cart or the sled may be transferred to the plurality of elongated support surfaces of the other of the transportation cart and the sled, at least a portion of said plurality of elongated support surfaces of the transportation cart and the at least one module being sized and disposable to intermesh to create a joint sheet support surface such that sheets or stacks of sheets disposed on the plurality of elongated support surfaces of one of the transportation cart or the at least one module may be transferred to the plurality of elongated support surfaces of the other of the transportation cart and the at least one module, whereby said successive sheets or stacks of sheets are moved between the transportation cart and the sled, and between the transportation cart and the at least one module in the sheet handling system.
 18. The sheet handling system of claim 17 further comprising at least one low friction support disposed subjacent at least a portion of the lower surface of the sled, the low friction support supporting the sled on the platform and facilitating relative movement between the sled lower surface and the platform.
 19. The sheet handling system of claim 18 wherein the low friction support comprises at least one of a polytetrafluoroethylene surface, caster, roller, or ball bearing.
 20. The sheet handling system of claim 17 wherein the modular processing station comprises an elevator disposed to move the platform in a substantially vertical direction
 21. The sheet handling system of claim 20 further comprising a locking arrangement, the locking arrangement being disposed to selectively limit relative movement between the sled and the platform.
 22. The sheet handling system of claim 21 wherein the platform comprises an edge, and the locking arrangement secures the sled to the edge of the platform.
 23. The sheet handling system of claim 21 wherein the locking arrangement comprises at least one bracket secured to the platform and the sled comprises at least one slot, the slot being disposed and sized to slide along the bracket.
 24. The sheet handling system of claim 21 wherein the locking arrangement comprises at least a hook, the hook being coupled to the sled and disposed and sized to selectively engage the edge of the platform.
 25. The sheet handling system of claim 17 wherein the modular processing station comprises a second sled comprising the plurality of elongated support surfaces of the at least one module.
 26. A method of adapting an existing processing station for use in a sheet stack handling system for processing a stack of sheets, the handling system comprising a transportation cart and at least one module selected from the group consisting of an elevator transfer station, a modular transfer station, a storage station, and a second modular processing station for performing an operation on said successive sheets or stacks of sheets, said at least one module and said cart each comprising a plurality of elongated support surfaces disposed to collectively present respective sheet support surfaces, at least a portion of said plurality of elongated support surfaces of the transportation cart and the at least one module being sized and disposable to intermesh to create a joint sheet support surface such that sheets or stacks of sheets disposed on the plurality of elongated support surfaces of one of the transportation cart and the at least one module may be transferred to the plurality of elongated support surfaces of the other of the transportation cart and the at least one module, the method comprising the steps of providing a sled comprising a plurality of elongated support surfaces collectively presenting a sled sheet support surface, at least a portion of said plurality of elongated support surfaces of the transportation cart and the sled being sized and disposable to intermesh to create a joint sheet support surface such that the stack of sheets disposed on the plurality of elongated support surfaces of one of the transportation cart or the sled may be transferred to the plurality of elongated support surfaces on another of the transportation cart or the sled, supporting said sled on a platform of the existing processing station, the sled being movable in at least one direction in a plane parallel to the platform.
 27. The method of claim 26 further comprising the step of providing the existing processing station with the platform.
 28. The method of claim 27 further comprising the step of locking the sled to the platform while transferring the stack of sheets between the transportation cart and the sled.
 29. The method of claim 27 wherein the sled is movable in more than one direction in a plane parallel to the platform.
 28. The method of claim 27 wherein the locking step comprises the step of sliding slots in the sled along brackets to advance the sled to an edge of the platform.
 29. The method of claim 27 wherein the locking step comprises the step of engaging a hook coupled to the sled to an edge of the platform. 